Re: iBook and playing DVDs
On 15 May 2002 00:05:59 +0200
Michel D <daenzer@debian.org> wrote:
> On Mon, 2002-05-13 at 22:04, Rogério Brito wrote:
> > On May 12 2002, Michel Dänzer wrote:
> > >
> > > Well, the actual movies shouldn't be interlaced.
> >
> > Well, I read that also in Ben's reply and got surprised, since
> > without exception all DVDs that I have seen to this day are
> > interlaced.
>
> Sounds like bad encodings. The original movies as shown in theaters obviously
> aren't interlaced so if a DVD is that's purely artificial.
Are you sure about this? I thought most DVDs carried either interlaced
NTSC or interlaced PAL. In the NTSC case the movie is converted to
30fps interlaced by a 3:2 pulldown (3 fields from one frame, 2 fields
from the next). In the PAL case each frame is split into two fields,
which speeds the film up slightly. Adjusting the pitch of the audio is
optional in this case. I believe that in both cases this is normally
done when mastering the DVD, to allow for manual tweaking of the
process.
To play back NTSC material sourced from 24fps film on a progressive scan
display the player needs to do an inverse telecine transformation. Do
any of the Linux players support this?
For examples of why inverse telecine is hard, see:
http://www.lukesvideo.com/telecining4.html
- Adrian Cox
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